Washington — Sen. Edward Kennedy (D) of Massachusetts ended the third longest career in US Senate history in a way few predicted when he began it – out of the shadow of two larger-than-life brothers and with a run of legislative achievements second to none.

From civil rights and immigration, his earliest concerns, to education and workers rights, there were few major pieces of social legislation that did not bear his mark over his 47 years in the Senate.

But the issue the lifelong Democrat called “the cause of my life” was healthcare. It was what kept him on the line to the Capitol through months of medical treatment during the past 15 months. He would not live to see his latest bid for comprehensive healthcare insurance enacted into law.

He gave his first speech for universal health insurance in 1969 and, as chairman of the Senate's health subcommittee, helped launch the war on cancer in 1971. His Americans with Disabilities Act, passed in 1990, banned discrimination in hiring.

For those familiar only with his decades as lion of the Senate, it’s hard to recreate the not-so-great expectations that dogged his early years as a senator, after he was elected in 1962 to replace his brother, President John Kennedy.

“When I did my first sabbatical in the Senate, I was told anything Kennedy did would get 30 votes, out of respect for this brothers and the Kennedy family name, but would never get a majority,” says Ross Baker, a political scientist at Rutgers University in New Brunswick, N.J. “That’s no longer the case. He became a maker of majorities with the most unlikely partners."

With Sen. Orrin Hatch (R) of Utah, a leading conservative, Kennedy moved some of America’s most important health legislation through the Senate Labor Committee (now the Health, Education, Labor and Pensions Committee), including a landmark bill to ensure healthcare for poor children.

“Ted Kennedy, with all of his ideological verbosity and idealism, was a rare person who at times could put aside differences and look for common solutions,” said Senator Hatch in a statement Wednesday. "Not many got to see that side of him, but as peers and colleagues we were able to share some of those moments.”

With President Bush, he helped pass the historic No Child Left Behind Act, which required that poor children be tested in reading and math to ensure they are making “adequate yearly progress.”

Kennedy told biographers that the biggest mistake of his public life was not working with President Nixon on healthcare in the early 1970s, when Nixon proposed universal coverage. At the time, Kennedy was a front-runner for the presidency in 1980 and thought that waiting might get the nation a better bill.

While Kennedy would lead polls for the Democratic presidential nomination for decades, his prospects took a hit after he fled the scene of an accident on a bridge in Chappaquiddick in 1969, leaving a young woman, Mary Jo Kopechne, to drown.

After losing the 1980 Democratic presidential primary to Jimmy Carter, Kennedy refocused on his energies on the Senate. On Aug. 13, President Obama dubbed Kennedy an “agent of change,” as he awarded him, in absentia, the Medal of Freedom.

"An important chapter in our history has come to an end,” said President Obama said in a written statement. “Our country has lost a great leader, who picked up the torch of his fallen brothers and became the greatest United States senator of our time.

“For five decades, virtually every major piece of legislation to advance the civil rights, health and economic well being of the American people bore his name and resulted from his efforts."